/* ========================================================================
   策问Meno — Launch Site · "Liquid Glass × Claude"
   Tokens from docs/DESIGN.md. Plain CSS, no build step.
   ===================================================================== */

:root {
  /* brand gradient */
  --indigo-900: #241E47;
  --indigo-700: #352B68;
  --violet-600: #5B4B9E;
  --violet-400: #8B79C9;
  /* gold accent */
  --gold-500: #E8B84B;
  --gold-300: #F4D27E;
  /* claude warmth */
  --paper-50: #FBF9F4;
  --paper-100: #F2EEE3;
  --clay-500: #D97757;
  /* ink */
  --ink: #F4F2FB;
  --ink-muted: #BDB8D4;
  /* glass */
  --glass-fill: rgba(255, 255, 255, 0.10);
  --glass-fill-strong: rgba(255, 255, 255, 0.15);
  --glass-border: rgba(255, 255, 255, 0.18);
  --glass-shadow: 0 12px 32px rgba(36, 30, 71, 0.28);
  /* rhythm */
  --r-card: 24px;
  --r-pill: 999px;
  --r-btn: 18px;
  --maxw: 1080px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
          "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
          "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  color: var(--ink);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  background:
    radial-gradient(120% 90% at 80% -10%, rgba(139, 121, 201, 0.35), transparent 55%),
    radial-gradient(100% 80% at 0% 0%, rgba(232, 184, 75, 0.10), transparent 50%),
    linear-gradient(150deg, var(--indigo-900) 0%, var(--indigo-700) 45%, var(--violet-600) 100%);
  background-attachment: fixed;
  min-height: 100vh;
  overflow-x: hidden;
}

img { max-width: 100%; display: block; }

a { color: inherit; text-decoration: none; }

/* ---------- floating orbs ---------- */
.orbs { position: fixed; inset: 0; z-index: 0; pointer-events: none; overflow: hidden; }
.orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.45;
  animation: drift 22s ease-in-out infinite alternate;
}
.orb--violet  { width: 460px; height: 460px; background: var(--violet-400);
  top: -120px; left: -80px; opacity: 0.4; }
.orb--gold    { width: 360px; height: 360px; background: var(--gold-500);
  top: 38%; right: -120px; opacity: 0.18; animation-delay: -7s; }
.orb--violet2 { width: 420px; height: 420px; background: var(--violet-600);
  bottom: -160px; left: 30%; opacity: 0.35; animation-delay: -14s; }

@keyframes drift {
  from { transform: translate3d(0, 0, 0) scale(1); }
  to   { transform: translate3d(40px, -30px, 0) scale(1.08); }
}

/* ---------- glass primitive ---------- */
.glass {
  background: var(--glass-fill);
  -webkit-backdrop-filter: blur(28px) saturate(1.2);
  backdrop-filter: blur(28px) saturate(1.2);
  border: 1px solid var(--glass-border);
  box-shadow: var(--glass-shadow), inset 0 1px 0 rgba(255, 255, 255, 0.22);
  border-radius: var(--r-card);
}

/* ---------- buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  border-radius: var(--r-btn);
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
  will-change: transform;
}
.btn--sm { padding: 9px 18px; font-size: 14px; }
.btn--gold {
  background: linear-gradient(180deg, var(--gold-300), var(--gold-500));
  color: var(--indigo-900);
  box-shadow: 0 8px 24px rgba(232, 184, 75, 0.32), inset 0 1px 0 rgba(255, 255, 255, 0.5);
}
.btn--gold:hover { transform: translateY(-2px); box-shadow: 0 12px 30px rgba(232, 184, 75, 0.42), inset 0 1px 0 rgba(255, 255, 255, 0.55); }
.btn--glass {
  background: var(--glass-fill-strong);
  color: var(--ink);
  border-color: var(--glass-border);
  -webkit-backdrop-filter: blur(20px);
  backdrop-filter: blur(20px);
}
.btn--glass:hover { transform: translateY(-2px); background: rgba(255, 255, 255, 0.2); }
.btn:active { transform: scale(0.97); }

/* ---------- header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 24px;
  padding: 14px clamp(16px, 5vw, 40px);
  background: rgba(36, 30, 71, 0.45);
  -webkit-backdrop-filter: blur(24px);
  backdrop-filter: blur(24px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.brand { display: flex; align-items: center; gap: 10px; }
.brand__icon { border-radius: 9px; }
.brand__word { font-size: 22px; font-weight: 700; letter-spacing: 0.3px; }
.brand__dot { color: var(--gold-500); }

.nav { display: flex; gap: 26px; margin-left: auto; font-size: 15px; color: var(--ink-muted); }
.nav a { transition: color 0.15s ease; }
.nav a:hover { color: var(--ink); }

.header__actions { display: flex; align-items: center; gap: 12px; }
.lang-toggle {
  padding: 7px 12px;
  font-size: 13px;
  font-weight: 600;
  color: var(--ink);
  cursor: pointer;
  border-radius: var(--r-pill);
  line-height: 1;
}
.lang-toggle__sep { opacity: 0.45; margin: 0 2px; }
.lang-toggle .lang-toggle__zh,
.lang-toggle .lang-toggle__en { opacity: 0.5; transition: opacity 0.15s ease; }
html[lang="zh"] .lang-toggle__zh,
html[lang="en"] .lang-toggle__en { opacity: 1; color: var(--gold-300); }

/* ---------- layout ---------- */
main { position: relative; z-index: 1; }
.section {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(56px, 9vw, 100px) clamp(16px, 5vw, 40px);
}
.section__title {
  font-size: clamp(26px, 4vw, 36px);
  font-weight: 700;
  text-align: center;
  margin: 0 0 12px;
  letter-spacing: 0.2px;
}
.section__sub {
  text-align: center;
  color: var(--ink-muted);
  font-size: 17px;
  margin: 0 auto clamp(36px, 5vw, 56px);
  max-width: 600px;
}

/* ---------- hero ---------- */
.hero {
  position: relative;
  z-index: 1;
  text-align: center;
  max-width: 820px;
  margin: 0 auto;
  padding: clamp(48px, 8vw, 96px) clamp(16px, 5vw, 40px) clamp(24px, 5vw, 48px);
}
.hero__icon-wrap { display: inline-block; position: relative; }
.hero__icon {
  width: 132px; height: 132px;
  border-radius: 30px;
  box-shadow: 0 20px 50px rgba(36, 30, 71, 0.55), inset 0 1px 0 rgba(255, 255, 255, 0.2);
  animation: float 6s ease-in-out infinite;
}
@keyframes float { 0%,100% { transform: translateY(0); } 50% { transform: translateY(-10px); } }

.hero__wordmark {
  font-size: clamp(48px, 9vw, 84px);
  font-weight: 800;
  margin: 28px 0 18px;
  letter-spacing: -0.5px;
  line-height: 1.05;
}
.hero__wordmark .dot { color: var(--gold-500); margin: 0 4px; }
.hero__alt {
  background: linear-gradient(180deg, var(--gold-300), var(--gold-500));
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: var(--gold-500);
}
.hero__tagline {
  font-size: clamp(17px, 2.4vw, 21px);
  color: var(--ink-muted);
  max-width: 640px;
  margin: 0 auto 34px;
  line-height: 1.7;
}
.hero__cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.hero__byok {
  display: inline-flex; align-items: center; gap: 9px;
  margin: 30px auto 0;
  font-size: 14px; color: var(--ink-muted);
}
.glass-pill {
  padding: 9px 18px;
  border-radius: var(--r-pill);
  background: var(--glass-fill);
  border: 1px solid var(--glass-border);
  -webkit-backdrop-filter: blur(20px); backdrop-filter: blur(20px);
}
.dot-spark { width: 8px; height: 8px; border-radius: 50%;
  background: var(--gold-500); box-shadow: 0 0 12px var(--gold-500); flex: none; }

/* ---------- core loop ---------- */
.loop {
  list-style: none; margin: 0; padding: 0;
  display: flex; flex-wrap: wrap; align-items: center; justify-content: center;
  gap: 12px;
}
.loop__step {
  display: flex; flex-direction: column; align-items: center; gap: 4px;
  padding: 16px 20px; min-width: 92px;
  font-size: 16px; font-weight: 600;
  transition: transform 0.2s ease;
}
.loop__step:hover { transform: translateY(-4px); }
.loop__i { font-size: 11px; font-weight: 700; color: var(--ink-muted); letter-spacing: 1px; }
.loop__step--accent {
  border-color: rgba(232, 184, 75, 0.55);
  box-shadow: var(--glass-shadow), inset 0 1px 0 rgba(255, 255, 255, 0.22), 0 0 0 1px rgba(232,184,75,0.25);
}
.loop__step--accent .loop__i { color: var(--gold-300); }
.loop__arrow { color: var(--gold-500); font-size: 18px; opacity: 0.8; }

/* ---------- features grid ---------- */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}
.card { padding: 28px 26px; transition: transform 0.2s ease, box-shadow 0.2s ease; }
.card:hover { transform: translateY(-6px); box-shadow: 0 20px 44px rgba(36, 30, 71, 0.38), inset 0 1px 0 rgba(255,255,255,0.24); }
.card--wide { grid-column: 1 / -1; }
.card__ic {
  width: 52px; height: 52px; border-radius: 15px;
  display: grid; place-items: center; font-size: 26px;
  background: rgba(232, 184, 75, 0.14);
  border: 1px solid rgba(232, 184, 75, 0.28);
  margin-bottom: 16px;
}
.card h3 { margin: 0 0 9px; font-size: 19px; font-weight: 700; }
.card p { margin: 0; color: var(--ink-muted); font-size: 15.5px; }

/* ---------- how it works ---------- */
.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}
.step { padding: 32px 28px; position: relative; }
.step__n {
  display: grid; place-items: center;
  width: 44px; height: 44px; border-radius: 50%;
  font-size: 20px; font-weight: 800; color: var(--indigo-900);
  background: linear-gradient(180deg, var(--gold-300), var(--gold-500));
  margin-bottom: 18px;
  box-shadow: 0 6px 16px rgba(232, 184, 75, 0.3);
}
.step h3 { margin: 0 0 8px; font-size: 19px; }
.step p { margin: 0; color: var(--ink-muted); font-size: 15.5px; }

/* ---------- platforms ---------- */
.platforms {
  display: flex; flex-wrap: wrap; gap: 16px; justify-content: center;
}
.platform {
  display: flex; align-items: center; gap: 10px;
  padding: 18px 28px; font-size: 17px; font-weight: 600;
  transition: transform 0.2s ease;
}
.platform:hover { transform: translateY(-4px); }
.platform__ic { width: 10px; height: 10px; border-radius: 50%;
  background: var(--gold-500); box-shadow: 0 0 10px var(--gold-500); }

/* ---------- download band ---------- */
.cta-band {
  max-width: var(--maxw); margin: 0 auto;
  text-align: center;
  padding: clamp(48px, 7vw, 72px) clamp(24px, 5vw, 56px);
  background: var(--glass-fill-strong);
}
.cta-band__title { font-size: clamp(24px, 4vw, 34px); font-weight: 700; margin: 0 0 12px; }
.cta-band__sub { color: var(--ink-muted); font-size: 17px; margin: 0 auto 30px; max-width: 480px; }
.cta-band__actions { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.cta-band__note { margin: 22px 0 0; font-size: 13px; color: var(--ink-muted); letter-spacing: 0.5px; }

/* ---------- footer ---------- */
.site-footer {
  position: relative; z-index: 1;
  max-width: var(--maxw); margin: 0 auto;
  padding: 40px clamp(16px, 5vw, 40px) 56px;
  display: flex; flex-wrap: wrap; align-items: center; gap: 18px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  color: var(--ink-muted); font-size: 14px;
}
.footer__brand .brand__word { font-size: 18px; }
.footer__links { display: flex; gap: 22px; margin: 0 auto; }
.footer__links a:hover { color: var(--ink); }
.footer__copy { margin: 0; }

/* ---------- scroll reveal ---------- */
.section, .footer__brand { opacity: 1; }
.reveal { opacity: 0; transform: translateY(24px); transition: opacity 0.7s ease, transform 0.7s ease; }
.reveal.is-visible { opacity: 1; transform: none; }

/* ---------- responsive ---------- */
@media (max-width: 760px) {
  .nav { display: none; }
  .loop__arrow { transform: rotate(90deg); }
  .loop { flex-direction: column; }
  .loop__step { width: 100%; max-width: 240px; flex-direction: row; justify-content: center; gap: 10px; }
}

/* ---------- reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .orb, .hero__icon { animation: none; }
  .reveal { opacity: 1; transform: none; transition: none; }
  .btn, .card, .platform, .loop__step { transition: none; }
}